Technical Field
The disclosure relates to a semiconductor structure, and in particular it relates to a semiconductor structure simultaneously including a low-voltage MOS device and a high-voltage MOS device and method for manufacturing the same.
Description of the Related Art
Manufacturers of electronic goods are under constant pressure to supply devices having expanded functionality and lower prices. One example is the cell phone, where staunch competition between manufacturers and re-sellers has kept cell phone prices down even as the cell phone functions have expanded dramatically. Indeed, a cell phone now includes such capabilities as e-mail, web-browsing, text-messaging, music storage, photography, and video playback.
In order to facilitate the trend towards expanded device functionality at lower prices, manufacturers must develop not only new processing architectures and algorithms, but also new semiconductor technologies allowing denser device integration at lower fabrication costs. However, increased device integration often requires a blending of heretofore incompatible technologies into a common device substrate.
Many electronic devices such as cell phones include low-voltage CMOS devices in various circuitry (e.g., data encryption and decryption). However, the same electronic devices also include relatively high-voltage devices in another circuitry (e.g., modulators/demodulators and power amplifiers). Unfortunately, high-voltage devices do not generally function effectively at low-voltages, and the low-voltage devices can be damaged by high voltages. These facts often result in the conventional provision of separate integrated circuits, one implemented in low-voltage devices and another implemented in high-voltage devices. However, such an approach to dealing with the common provision of different types of devices are simply not possible under emerging pressures related to integration densities and fabrication costs.
Many skills have been developed to overcome the problems described above. However, conventional skills have to change the doping concentrations of different doping regions while the driving voltage of the high-voltage device is changed. The difficulty and cost of changing the doping concentration is higher than designing new photo masks and corresponding doping region profiles. In other words, a structure including a high-voltage device and low-voltage device is usually suitable for specific high voltage and low voltage, which cannot be easily modified while changing the driving voltage of the product.
Accordingly, a novel process and a corresponding structure for fine-tuning the structure corresponding to different driving voltages (without increasing the number of photo masks or changing the doping concentration of the doping regions) are called for.